Foldable Display Protective Film with Variable Adhesion
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Solution Overview
Problem
Conventional foldable display protective films face challenges in maintaining adequate adhesive strength during use while allowing for easy removal without damaging the display device, as excessive adhesive strength can lead to detachment during folding and unfolding, and insufficient strength may result in damage during peeling.
Innovation Solution
A foldable display protective film with an adhesive layer composed of a (meth)acrylate resin copolymerized from an alkyl (meth)acrylate monomer, a crosslinkable functional group-containing monomer, and a photoinitiator monomer, where the photoinitiator is present in a specific weight percentage, allowing for controlled adhesive strength reduction upon UV light exposure, ensuring strong attachment and gradual weakening for easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive strength of the protective film is increased to prevent detachment during folding and unfolding, then the reliability during use is improved, but the ease of removal deteriorates as damage may occur when peeling
Solution Approach 1:
The adhesive strength of the protective film is made dynamic through light-responsive control. The adhesive layer contains photoinitiators that enable reversible crosslinking: under visible light the adhesive maintains strong bonding for reliable attachment during device use, while under UV light the crosslinking is reversed to reduce adhesive strength for easy removal without damage. This dynamic adjustment resolves the contradiction between maintaining reliability during use and enabling ease of removal.
Solution Approach 2:
The adhesive strength parameter is changed on demand through light irradiation. The adhesive composition includes photoinitiators (such as benzophenone derivatives) that alter the adhesive's molecular structure when exposed to specific wavelengths. Visible light maintains the adhesive in a crosslinked state with high strength, while UV light triggers de-crosslinking to reduce strength, allowing the same adhesive layer to provide both strong attachment during use and easy removal when needed.
2Ease of operation
If the adhesive strength is decreased to enable easy removal without damage, then the ease of removal is improved, but the reliability deteriorates as the protective film may detach during folding and unfolding
Solution Approach 1:
The adhesive strength is dynamically controlled through light exposure timing. During normal device use, the adhesive remains in a high-strength crosslinked state to ensure reliable attachment through folding and unfolding cycles. When removal is desired, UV light irradiation dynamically switches the adhesive to a low-strength state, enabling easy peeling without damage. This temporal control of adhesive strength resolves the contradiction between reliability during use and ease of removal.
Solution Approach 2:
The adhesive layer is pre-designed with photoinitiators and crosslinkable functional groups that enable controlled strength reduction. Before removal is needed, the adhesive structure is prepared with light-responsive components that will trigger de-crosslinking when UV light is applied. This preliminary preparation of the adhesive composition allows for on-demand strength reduction without compromising initial attachment reliability.
3Ease of operation
If a high concentration of photoinitiator is used to enable significant adhesive strength reduction, then the ease of removal is improved, but the manufacturing precision deteriorates as the initial adhesive strength may be insufficient
Solution Approach 1:
The photoinitiator concentration is optimized to a specific range (0.1-5 wt%, preferably 0.5-3 wt%) to balance two opposing requirements: sufficient initial adhesive strength for reliable attachment and adequate light-responsive capability for strength reduction upon removal. This precise parameter control ensures that the adhesive composition achieves both high initial bonding and effective removable upon UV exposure, resolving the contradiction between ease of removal and manufacturing precision.
Solution Approach 2:
The adhesive layer is designed as a composite material containing multiple components: base adhesive polymers, crosslinkable functional groups, and photoinitiators in specific proportions. This composite structure enables the adhesive to exhibit high initial strength through crosslinking while maintaining light-responsive properties for controlled de-crosslinking. The synergistic combination of components resolves the contradiction between maintaining initial adhesive strength and enabling significant strength reduction for easy removal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film maintains high initial adhesive strength for secure attachment and gradually decreases with UV exposure, enabling safe peeling without damaging the cover window, while maintaining sufficient strength during repeated folding and unfolding.
Implementation Method 1
an adhesive layer including an adhesive composition including a (meth)acrylate resin produced by copolymerization of a mixture containing an alkyl (meth)acrylate monomer, a crosslinkable functional group-containing monomer, and a photoinitiator monomer
Data Source
AI summary
The present disclosure provides a foldable display protective film having variable adhesive strength and a foldable display device including the same.